Test Could Become Another Tool to Fine Tune Immune Suppressing Drugs
MAYWOOD, Ill. - Doctors play a delicate balancing act when prescribing immune-suppressing drugs to organ transplant patients.
The drugs must be strong enough to suppress the immune system so the patient doesn't reject the transplanted organ, but not so strong the patient becomes vulnerable to infections.
A new blood test might help doctors strike the proper balance, according to researchers at Loyola University Medical Center, who evaluated the test.
The test measures the energy level of immune-system cells called lymphocytes. In the Loyola study, researchers found that patients with high-energy lymphocytes did not develop infections. Those with low-energy lymphocytes were vulnerable to infections such as pneumonia, urinary tract infections, herpes and skin infections.
Loyola cardiologist Dr. Biljana Pavlovic-Surjancev gave a poster presentation summarizing the findings at the American Transplant Congress in Toronto on May 31, 2008. The congress is the joint annual meeting of the American Society of Transplant Surgeons and the American Society of Transplantation.Pavlovic-Surjancev is an assistant professor of medicine in the Division of Cardiology, Heart Failure/Heart Transplant Program, at Loyola University Chicago Stritch School of Medicine.
Doctors traditionally have monitored the immune system by counting the number of immune cells in a given sample. The new test monitors just how active those cells are by measuring an energy-carrying molecule called adenosine triphosphate, or ATP, that's released from the cells. The higher the ATP level, the more active the cells.
The Loyola team analyzed 37 samples from 26 heart transplant patients. Fifteen patients with infections had lower ATP levels than eleven patients who did not have infections. Patients with infections also had low immune cell counts.
"Infection is associated with a low level of immune cell function in this small study," Pavlovic-Surjancev said. "It will take additional studies to find out if this test can help us see the risk of infection before infection occurs."
Authors of the study, all from Loyola, are Biljana Pavlovic-Surjancev, MD, PhD; Prasanth Lingam, MD; Nilamkumar Patel, MBBS; David Marmor, MD; James Sinacore, Ph.D.; Brian Susskind, Ph.D; and senior author Alain Heroux, MD. Heroux is associate professor of medicine in the Division of Cardiology at Loyola University Chicago Stritch School of Medicine and Medical Director of Loyola Heart Failure/Heart Transplant Program.
Loyola has done more than 600 heart transplants since 1984.
Authors of the study have reported no financial conflicts or disclosures.
The ATP test, called ImmuKnowÂ®, is manufactured by Cylex(tm) Inc.